Polyolefin resins such as polyethylene and polypropylene are non-polar and have no polar group to which a dye can bonds. Accordingly, they cannot be dyed. It has been desired to make such polymers dyeable, since such polymers were developed.
Conventionally, a pigment is added to such polymers before shaping, such as spinning, to give color to the polymers. This method lacks such flexibility as to adapt coloring to catch up with the change of needs in the market. Variety of colors are less, compared to dyeing with dyes. For these reasons, applications of polyolefin resins, such as polypropylene fiber, are limited, compared to dyeable resins.
Some fibers such as polyurethane fiber are dyeable, but their dyabilities are relatively low. Polyurethane fiber is usually used in a blend with nylon or polyester. Then, uneven color occurs between the polyurethane fiber and nylon or polyester fiber, which decreases a commercial value of the product
In order to solve the aforesaid problems in dyeablity of such resins or fibers, the present inventor invented the technology where hydrotalcite type material is added to a resin, melt mixed, shaped, e.g., spun, and then dyed with anionic dyes i.e., acidic dyes, taking advantage of the anion-exchanging ability of hydrotalcite type material. The technology is disclosed in the following three literatures.
Japanese Patent Application Laid-Open No. 2000-119510 discloses a composition having good dyeablity, and comprising polyurethane and 0.1 to 20% by weight of a hydrotalcite type material in which intercalating anions are mono_ or di_valent anions such as NO3−, Cl−, Br−, ClO4−, HCOO−, CH3COO− and SO42—.
Japanese Patent Application Laid-Open No. 2007-303025 discloses an elastic polyurethane fiber composition comprising polyurethane and 0.1 to 20% by weight of a hydrotalcite type material in which intercalating anions are ions of a carboxylic acid having an aromatic group or ions of an aromatic aminesulfonic acid.
Japanese Patent Application Laid-Open No. 2008-163491 discloses a fiber composition comprising 0.1 to 20% by weight of a hydrotalcite type material in which intercalating anions are ions of a C10-25 higher aliphatic acid.